The Global Positioning Satellite (GPS) system is a global satellite based system maintained and operated by the United States government by which a GPS receiver can receive transmissions from the satellites and determine its position on earth with a high degree of accuracy. As a result of a recent lifting of restrictions on the positioning resolution of the system, an individual carrying a GPS receiver can now pinpoint his or her position on the earth within approximately a 20 to 25 foot radius.
In operation, a GPS receiver receives transmissions from two or more of the geo-stationary GPS satellites and, through the use of triangulation, can determine the position of the receiver relative to the satellites. More particularly, each satellite transmits a signal that includes information as to what particular satellite is transmitting the signal and the timing of the signal. A GPS receiver receiving signals from two or more satellites can determine the length of time each signal took to reach the receiver for each satellite and, by the running a mathematical triangulation algorithm on the received data, pinpoint the location of the receiver relative to the satellites. Original GPS systems were relatively bulky and thus typically vehicle mounted. They were originally used in military applications, such as aircraft and missiles. They have since become common for use in navigation systems in automobiles. Eventually, the electronics of the receivers became inexpensive and small enough that there are now many commercially available palm-top GPS receivers. Typically a user of a GPS system must manually input his elevation relative to mean sea level in order for the device to work most accurately.
Wireless two-way communication systems have also been in wide use for many years. Two-way short-wave radios such as walkie-talkies have been in use among the military and civilian population for many decades and provide reasonable two way communications between two transceivers within a relatively short distance of each other. Depending on the sophistication, size and power of the unit, and the local terrain, walkie-talkies typically have a range of approximately one-quarter mile to ten miles. Cellular telephone systems are another form of personal, wireless, two-way communication system. As is well known to those of skill in the art, an individual carrying a cellular transceiver (e.g., a cell phone) can transmit and receive data from a stationary base station within a certain distance of his or her location (typically no more than five miles). The base station comprises a wireless transceiver capable of supporting many channels simultaneously and also is coupled to convert and switch signals in both directions between the wireless communication system and the wired telephone network. Thus, when someone makes a cellular telephone call, that individual carries on a two-way wireless communications session between the hand held cellular telephone and the base station. The base station carries on a two-way wire-based communication of the same content with the other termination point of the communication link. Of course, if the other termination point is another cellular telephone, then, at the opposite end, the signals transmitted and received via the wired telephone network are sent to another cellular base station and further transmitted and received over another wireless connection between another cellular telephone and that base station.
Systems have been devised for integrating a GPS system and a one-way communication system to provide various services to individuals and businesses. For instance, U.S. Pat. No. 6,185,504 discloses a vehicle scheduling and collision avoidance system using GPS and one-way cellular-based communication. Also, U.S. Pat. No. 6,043,777 discloses a GPS-based cooperative location system which uses two-way communication in that certain units are receivers and other units are transmitters, but none are both transmitters and receivers (i.e., transceivers).
It is an object of the present invention to provide a method and apparatus utilizing GPS or any other positioning system for locating individuals and a two-way communication system for enhancing safety among outdoor recreationists.
It is another object of the present invention to provide a method and apparatus utilizing GPS or any other positioning system for locating individuals and a two-way communication system for enhancing safety among hunters.
It is an further object of the present invention to provide a method and apparatus utilizing GPS or any other positioning system for locating individuals and a two-way communication system to allow multiple individuals in a party to determine the location of other individuals in their party.